The present invention relates to a load adjustment device having a control element for action on at least one setting member which determines the output of an internal combustion engine. The control element is spring-coupled with a driver actuated by an accelerator pedal and, furthermore, is moveable by means of an electric setting drive. The control element has a desired-value detection element associated with the driver, and has an actual-value detection element cooperating with the desired-value detection element and acting on the electric setting drive. The electric setting drive is adapted to be controlled by an electronic control device as a function of the values detected.
Such a load adjustment device is known from Federal Republic of Germany patent document 38 15 734 A1. It serves the purpose of replacing the customary control of a setting member on the accelerator-pedal side under certain operating conditions of the internal combustion engine or of the vehicle driven by it by a setting drive controlled by the control electronics. Thus the electronic control device can, for instance, act in a manner to avoid wheel slippage upon starting as a result of excessive power. It is provided also that, upon too rapid a depression of the accelerator pedal, the setting member is more strongly controlled downward than corresponds to the position of the accelerator pedal, so that the internal combustion engine produces only a power which does not lead to the spinning of the wheels. Other automatic actions on the load adjustment device are necessary if a transmission is to be switched automatically or if the idling speed of rotation is to be adjusted to a constant value even upon different power requirements upon idling, for instance on the part of load-consuming devices provided in the vehicle. Finally, there is also the possibility, in the case of the load adjustment device, to act in the manner of a speed governor, which, due to the possibility of a disconnecting of the control element from the accelerator pedal, provides in each case a power which is necessary in order to maintain the speed set. In addition, it may be desirable from the standpoint of driving comfort to provide a progressive or degressive action of the accelerator pedal with the possibility of a power setting which is reduced or increased with respect to the accelerator pedal.
In the known load adjustment device, the control element cooperates with a setting element which is developed, for instance, as a throttle valve. In particular, in the event of control of the idling by means of the electric setting drive, the problem arises, when using a setting member, that a small angle of displacement of the throttle valve must be controlled by means of the setting drive. In order to satisfy this requirement, it is necessary to develop the electric setting drive with an expensive construction, which is true, in particular, when the setting drive is to cover not only the idling control range but also--as is necessary in the case of speed control--the partial-load and full-load ranges of the internal combustion engine.